Monday, August 24, 2015

On Registered Clinical Trials

A new PLoS ONE study looks at the effect of mandatory pre-registration of medical study methods and outcome measures, starting in 2000. Major findings:

Studies finding positive effects fell from 57% prior to the registry to just 8% afterward.

"...focused on human randomized controlled trials that were funded by the
US National Heart, Lung, and Blood Institute (NHLBI) [and so required advanced registration by a 1997 U.S. law]. The authors
conclude that registration of trials seemed to be the dominant driver of
the drastic change in study results."

"Steven Novella of Yale University in New Haven, Connecticut, called the
study 'encouraging' but also 'a bit frightening' because it casts doubt
on previous positive results...”

"Many online observers applauded the evident power of registration and
transparency, including Novella, who wrote on his blog that all research
involving humans should be registered before any data are collected.
However, he says, this means that at least half of older, published
clinical trials could be false positives. 'Loose scientific methods are
leading to a massive false positive bias in the literature,' he writes."